title: The inhibition effect of high storage temperature on the recrystallization rate during dissolution of nimodipine-Kollidon VA64 solid dispersions (NM-SD) prepared by hot-melt extrusion.
abstract: Nimodipine (NM) solid dispersions (SD) were prepared by hot-melt extrusion with polyvinylpyrrolidone/vinyl acetate copolymer (PVP-VA; Kollidon VA64) as the carrier, then the extrudate was stored at different temperatures (20°C, 40°C, 60°C) after milling. Conventional differential scanning calorimetry and powder X-ray diffraction revealed that the drug was present as an amorphous state in the carrier. The dissolution curves of NM from SD at 37°C in water showed that the rate of recrystallization for NM from SD stored at high temperatures was slower than that from room temperature. The single glass transition temperature (T(g) ) measured by modulated temperature DSC remained constant around 89°C and indicated that the amorphous state of the compound was not altered by heating. However, the C=O vibration of the amide function of Kollidon VA64 increased from 1658 to 1675 cm(-1) was observed in infrared spectra and implied the weakness of H-bonding between the compound and the polymer. The above-mentioned experiments clued to us that suitable postcooking for a short time is good for SD; however, the mechanisms of the changes were still not clear and need further investigation.
authors.affiliation: Department of Pharmaceutics, Shenyang Pharmaceutical University, Shenyang 110016, Liaoning, People's Republic of China.
authors.forename: Fu
authors.initials: F
authors.lastname: Jijun
authors.forename: Xu
authors.initials: X
authors.lastname: Lishuang
authors.forename: Tao
authors.initials: T
authors.lastname: Xiaoguang
authors.forename: Su
authors.initials: S
authors.lastname: Min
authors.forename: Zhao
authors.initials: Z
authors.lastname: Mingming
authors.forename: He
authors.initials: H
authors.lastname: Haibing
authors.forename: Tang
authors.initials: T
authors.lastname: Xing
mesh_terms: D000959:Antihypertensive Agents / Q000737:chemistry*; D003460:Crystallization; D004355:Drug Stability; D005615:Freezing; D006358:Hot Temperature; D009553:Nimodipine / Q000737:chemistry*; D011759:Pyrrolidines / Q000737:chemistry; D012995:Solubility; D014753:Vinyl Compounds / Q000737:chemistry
chemical_list: D000959:Antihypertensive Agents; D011759:Pyrrolidines; D014753:Vinyl Compounds; C402301:poly(vinylpyrrolidone-co-vinyl-acetate); D009553:Nimodipine